1
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Jaiswal A, Singh R. CtBP: A global regulator of balancing acts and homeostases. Biochim Biophys Acta Rev Cancer 2023; 1878:188886. [PMID: 37001619 DOI: 10.1016/j.bbcan.2023.188886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 03/31/2023]
Abstract
The classical role of C-terminal binding protein (CtBP) is that of a global corepressor. However, its exact mechanism of repression is not known. In this review, we elucidate the repression motif used by CtBP. Further, we provide other unifying features of its mechanism of action. For example, in the presence of a high NADH/NAD+ ratio in the cell, causing a low glycolytic condition, the NADH-bound dimeric form of CtBP causes global repression, maintaining balances and homeostases of many cellular processes, under the cell surveillance of p53 and NFkB. In contrast, in the presence of a low NADH/NAD+ ratio, causing a high glycolytic condition, the NADH-free monomeric form of CtBP blocks p53 function and NFkB-mediated transcription. Further, a low NADH/NAD+ ratio upsets the homeostases and balances in the absence of the cell surveillances of p53 and NFkB, causing global instability, the dominant outcome of CtBP's action in carcinogenesis, in cells in a high glycolytic state.
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2
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Raicu AM, Kadiyala D, Niblock M, Jain A, Yang Y, Bird KM, Bertholf K, Seenivasan A, Siddiq M, Arnosti DN. The Cynosure of CtBP: Evolution of a Bilaterian Transcriptional Corepressor. Mol Biol Evol 2023; 40:msad003. [PMID: 36625090 PMCID: PMC9907507 DOI: 10.1093/molbev/msad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 12/16/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
Evolution of sequence-specific transcription factors clearly drives lineage-specific innovations, but less is known about how changes in the central transcriptional machinery may contribute to evolutionary transformations. In particular, transcriptional regulators are rich in intrinsically disordered regions that appear to be magnets for evolutionary innovation. The C-terminal Binding Protein (CtBP) is a transcriptional corepressor derived from an ancestral lineage of alpha hydroxyacid dehydrogenases; it is found in mammals and invertebrates, and features a core NAD-binding domain as well as an unstructured C-terminus (CTD) of unknown function. CtBP can act on promoters and enhancers to repress transcription through chromatin-linked mechanisms. Our comparative phylogenetic study shows that CtBP is a bilaterian innovation whose CTD of about 100 residues is present in almost all orthologs. CtBP CTDs contain conserved blocks of residues and retain a predicted disordered property, despite having variations in the primary sequence. Interestingly, the structure of the C-terminus has undergone radical transformation independently in certain lineages including flatworms and nematodes. Also contributing to CTD diversity is the production of myriad alternative RNA splicing products, including the production of "short" tailless forms of CtBP in Drosophila. Additional diversity stems from multiple gene duplications in vertebrates, where up to five CtBP orthologs have been observed. Vertebrate lineages show fewer major modifications in the unstructured CTD, possibly because gene regulatory constraints of the vertebrate body plan place specific constraints on this domain. Our study highlights the rich regulatory potential of this previously unstudied domain of a central transcriptional regulator.
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Affiliation(s)
- Ana-Maria Raicu
- Cell and Molecular Biology Program, Michigan State University, East Lansing, Michigan
| | - Dhruva Kadiyala
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Madeline Niblock
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | | | - Yahui Yang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Kalynn M Bird
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Kayla Bertholf
- Biochemistry and Molecular Biology Program, College of Wooster
| | - Akshay Seenivasan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Mohammad Siddiq
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan
| | - David N Arnosti
- Cell and Molecular Biology Program, Michigan State University, East Lansing, Michigan
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
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3
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Bi CL, Cheng Q, Yan LY, Wu HY, Wang Q, Wang P, Cheng L, Wang R, Yang L, Li J, Tie F, Xie H, Fang M. A prominent gene activation role for C-terminal binding protein in mediating PcG/trxG proteins through Hox gene regulation. Development 2022; 149:275613. [DOI: 10.1242/dev.200153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 04/28/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The evolutionarily conserved C-terminal binding protein (CtBP) has been well characterized as a transcriptional co-repressor. Herein, we report a previously unreported function for CtBP, showing that lowering CtBP dosage genetically suppresses Polycomb group (PcG) loss-of-function phenotypes while enhancing that of trithorax group (trxG) in Drosophila, suggesting that the role of CtBP in gene activation is more pronounced in fly development than previously thought. In fly cells, we show that CtBP is required for the derepression of the most direct PcG target genes, which are highly enriched by homeobox transcription factors, including Hox genes. Using ChIP and co-IP assays, we demonstrate that CtBP is directly required for the molecular switch between H3K27me3 and H3K27ac in the derepressed Hox loci. In addition, CtBP physically interacts with many proteins, such as UTX, CBP, Fs(1)h and RNA Pol II, that have activation roles, potentially assisting in their recruitment to promoters and Polycomb response elements that control Hox gene expression. Therefore, we reveal a prominent activation function for CtBP that confers a major role for the epigenetic program of fly segmentation and development.
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Affiliation(s)
- Cai-Li Bi
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
- Institute of Translational Medicine 2 , , , Yangzhou 225001 , China
- Medical College 2 , , , Yangzhou 225001 , China
- Yangzhou University 2 , , , Yangzhou 225001 , China
| | - Qian Cheng
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Ling-Yue Yan
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Hong-Yan Wu
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Qiang Wang
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Ping Wang
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Lin Cheng
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Rui Wang
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Lin Yang
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Jian Li
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Feng Tie
- Case Western Reserve University 3 Department of Genetics and Genome Sciences , , Cleveland, OH 44106, USA
| | - Hao Xie
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
| | - Ming Fang
- School of Life Science and Technology, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University 1 , Nanjing 210096 , China
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4
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Erlandsen H, Jecrois AM, Nichols JC, Cole JL, Royer WE. NADH/NAD + binding and linked tetrameric assembly of the oncogenic transcription factors CtBP1 and CtBP2. FEBS Lett 2022; 596:479-490. [PMID: 34997967 DOI: 10.1002/1873-3468.14276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/14/2021] [Accepted: 12/22/2021] [Indexed: 11/08/2022]
Abstract
The activation of oncogenic C-terminal binding Protein (CtBP) transcriptional activity is coupled with NAD(H) binding and homo-oligomeric assembly, although the level of CtBP assembly and nucleotide binding affinity continues to be debated. Here, we apply biophysical techniques to address these fundamental issues for CtBP1 and CtBP2. Our ultracentrifugation results unambiguously demonstrate that CtBP assembles into tetramers in the presence of saturating NAD+ or NADH with tetramer to dimer dissociation constants about 100 nm. Isothermal titration calorimetry measurements of NAD(H) binding to CtBP show dissociation constants between 30 and 500 nm, depending on the nucleotide and paralog. Given cellular levels of NAD+ , CtBP is likely to be fully saturated with NAD under physiological concentrations suggesting that CtBP is unable to act as a sensor for NADH levels.
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Affiliation(s)
- Heidi Erlandsen
- Center for Open Research Resources & Equipment, University of Connecticut, Storrs, CT, USA
| | - Anne M Jecrois
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, MA, USA
| | - Jeffry C Nichols
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, MA, USA.,Chemistry Department, Worcester State University, MA, USA
| | - James L Cole
- Department of Molecular and Cell Biology, Department of Chemistry, University of Connecticut, CT, USA
| | - William E Royer
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, MA, USA
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5
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Wu C, Ding X, Li Z, Huang Y, Xu Q, Zou R, Zhao M, Chang H, Jiang C, La X, Lin G, Li W, Xue L. CtBP modulates Snail-mediated tumor invasion in Drosophila. Cell Death Discov 2021; 7:202. [PMID: 34349099 PMCID: PMC8339073 DOI: 10.1038/s41420-021-00516-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/30/2021] [Accepted: 05/14/2021] [Indexed: 02/07/2023] Open
Abstract
Cancer is one of the most fatal diseases that threaten human health, whereas more than 90% mortality of cancer patients is caused by tumor metastasis, rather than the growth of primary tumors. Thus, how to effectively control or even reverse the migration of tumor cells is of great significance for cancer therapy. CtBP, a transcriptional cofactor displaying high expression in a variety of human cancers, has become one of the main targets for cancer prediction, diagnosis, and treatment. The roles of CtBP in promoting tumorigenesis have been well studied in vitro, mostly based on gain-of-function, while its physiological functions in tumor invasion and the underlying mechanism remain largely elusive. Snail (Sna) is a well-known transcription factor involved in epithelial-to-mesenchymal transition (EMT) and tumor invasion, yet the mechanism that regulates Sna activity has not been fully understood. Using Drosophila as a model organism, we found that depletion of CtBP or snail (sna) suppressed RasV12/lgl-/--triggered tumor growth and invasion, and disrupted cell polarity-induced invasive cell migration. In addition, loss of CtBP inhibits RasV12/Sna-induced tumor invasion and Sna-mediated invasive cell migration. Furthermore, both CtBP and Sna are physiologically required for developmental cell migration during thorax closure. Finally, Sna activates the JNK signaling and promotes JNK-dependent cell invasion. Given that CtBP physically interacts with Sna, our data suggest that CtBP and Sna may form a transcriptional complex that regulates JNK-dependent tumor invasion and cell migration in vivo.
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Affiliation(s)
- Chenxi Wu
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China.,College of Traditional Chinese Medicine, North China University of Science and Technology, 21 Bohai Road, Tangshan, 063210, China
| | - Xiang Ding
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Zhuojie Li
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Yuanyuan Huang
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Qian Xu
- College of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Rui Zou
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Mingyang Zhao
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China
| | - Hong Chang
- College of Traditional Chinese Medicine, North China University of Science and Technology, 21 Bohai Road, Tangshan, 063210, China
| | - Chunhua Jiang
- College of Traditional Chinese Medicine, North China University of Science and Technology, 21 Bohai Road, Tangshan, 063210, China
| | - Xiaojin La
- College of Traditional Chinese Medicine, North China University of Science and Technology, 21 Bohai Road, Tangshan, 063210, China
| | - Gufa Lin
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Wenzhe Li
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China.
| | - Lei Xue
- The First Rehabilitation Hospital of Shanghai, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai, 200092, China. .,Zhuhai Interventional Medical Center, Zhuhai Precision Medical Center, Zhuhai People's Hospital, Zhuhai Hospital Affiliated with Jinan University, Zhuhai, Guangdong, 51900, China.
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6
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Wan B, Belghazi M, Lemauf S, Poirié M, Gatti JL. Proteomics of purified lamellocytes from Drosophila melanogaster HopT um-l identifies new membrane proteins and networks involved in their functions. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 134:103584. [PMID: 34033897 DOI: 10.1016/j.ibmb.2021.103584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
In healthy Drosophila melanogaster larvae, plasmatocytes and crystal cells account for 95% and 5% of the hemocytes, respectively. A third type of hemocytes, lamellocytes, are rare, but their number increases after oviposition by parasitoid wasps. The lamellocytes form successive layers around the parasitoid egg, leading to its encapsulation and melanization, and finally the death of this intruder. However, the total number of lamellocytes per larva remains quite low even after parasitoid infestation, making direct biochemical studies difficult. Here, we used the HopTum-l mutant strain that constitutively produces large numbers of lamellocytes to set up a purification method and analyzed their major proteins by 2D gel electrophoresis and their plasma membrane surface proteins by 1D SDS-PAGE after affinity purification. Mass spectrometry identified 430 proteins from 2D spots and 344 affinity-purified proteins from 1D bands, for a total of 639 unique proteins. Known lamellocyte markers such as PPO3 and the myospheroid integrin were among the components identified with specific chaperone proteins. Affinity purification detected other integrins, as well as a wide range of integrin-associated proteins involved in the formation and function of cell-cell junctions. Overall, the newly identified proteins indicate that these cells are highly adapted to the encapsulation process (recognition, motility, adhesion, signaling), but may also have several other physiological functions (such as secretion and internalization of vesicles) under different signaling pathways. These results provide the basis for further in vivo and in vitro studies of lamellocytes, including the development of new markers to identify coexisting populations and their respective origins and functions in Drosophila immunity.
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Affiliation(s)
- Bin Wan
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Maya Belghazi
- Institute of NeuroPhysiopathology (INP), UMR7051, CNRS, Aix-Marseille Université, Marseille, 13015, France
| | - Séverine Lemauf
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Marylène Poirié
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France
| | - Jean-Luc Gatti
- Université Côte d'Azur, INRAE, CNRS, Institute Sophia-Agrobiotech, Sophia Antipolis, France.
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7
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Nichols JC, Schiffer CA, Royer WE. NAD(H) phosphates mediate tetramer assembly of human C-terminal binding protein (CtBP). J Biol Chem 2021; 296:100351. [PMID: 33524397 PMCID: PMC7949142 DOI: 10.1016/j.jbc.2021.100351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/22/2021] [Accepted: 01/27/2021] [Indexed: 12/27/2022] Open
Abstract
C-terminal binding proteins (CtBPs) are cotranscriptional factors that play key roles in cell fate. We have previously shown that NAD(H) promotes the assembly of similar tetramers from either human CtBP1 and CtBP2 and that CtBP2 tetramer destabilizing mutants are defective for oncogenic activity. To assist structure-based design efforts for compounds that disrupt CtBP tetramerization, it is essential to understand how NAD(H) triggers tetramer assembly. Here, we investigate the moieties within NAD(H) that are responsible for triggering tetramer formation. Using multiangle light scattering (MALS), we show that ADP is able to promote tetramer formation of both CtBP1 and CtBP2, whereas AMP promotes tetramer assembly of CtBP1, but not CtBP2. Other NAD(H) moieties that lack the adenosine phosphate, including adenosine and those incorporating nicotinamide, all fail to promote tetramer assembly. Our crystal structures of CtBP1 with AMP reveal participation of the adenosine phosphate in the tetrameric interface, pinpointing its central role in NAD(H)-linked assembly. CtBP1 and CtBP2 have overlapping but unique roles, suggesting that a detailed understanding of their unique structural properties might have utility in the design of paralog-specific inhibitors. We investigated the different responses to AMP through a series of site-directed mutants at 13 positions. These mutations reveal a central role for a hinge segment, which we term the 120s hinge that connects the substrate with coenzyme-binding domains and influences nucleotide binding and tetramer assembly. Our results provide insight into suitable pockets to explore in structure-based drug design to interfere with cotranscriptional activity of CtBP in cancer.
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Affiliation(s)
- Jeffry C Nichols
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA; Chemistry Department, Worcester State University, Worcester, Massachusetts, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - William E Royer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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8
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Jecrois AM, Dcona MM, Deng X, Bandyopadhyay D, Grossman SR, Schiffer CA, Royer WE. Cryo-EM structure of CtBP2 confirms tetrameric architecture. Structure 2020; 29:310-319.e5. [PMID: 33264605 DOI: 10.1016/j.str.2020.11.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/10/2020] [Accepted: 11/10/2020] [Indexed: 12/11/2022]
Abstract
C-terminal binding proteins 1 and 2 (CtBP1 and CtBP2) are transcriptional regulators that activate or repress many genes involved in cellular development, apoptosis, and metastasis. NADH-dependent CtBP activation has been implicated in multiple types of cancer and poor patient prognosis. Central to understanding activation of CtBP in oncogenesis is uncovering how NADH triggers protein assembly, what level of assembly occurs, and if oncogenic activity depends upon such assembly. Here, we present the cryoelectron microscopic structures of two different constructs of CtBP2 corroborating that the native state of CtBP2 in the presence of NADH is tetrameric. The physiological relevance of the observed tetramer was demonstrated in cell culture, showing that CtBP tetramer-destabilizing mutants are defective for cell migration, transcriptional repression of E-cadherin, and activation of TIAM1. Together with our cryoelectron microscopy studies, these results highlight the tetramer as the functional oligomeric form of CtBP2.
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Affiliation(s)
- Anne M Jecrois
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - M Michael Dcona
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Xiaoyan Deng
- Department of Biostatistics, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Dipankar Bandyopadhyay
- Department of Biostatistics, Virginia Commonwealth University, Richmond, VA 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Steven R Grossman
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - William E Royer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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9
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CtBP represses Dpp-dependent Mad activation during Drosophila eye development. Dev Biol 2018; 442:188-198. [PMID: 30031756 DOI: 10.1016/j.ydbio.2018.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 04/05/2018] [Accepted: 07/18/2018] [Indexed: 12/13/2022]
Abstract
Complex networks of signaling pathways maintain the correct balance between positive and negative growth signals, ensuring that tissues achieve proper sizes and differentiation pattern during development. In Drosophila, Dpp, a member of the TGFβ family, plays two main roles during larval eye development. In the early eye primordium, Dpp promotes growth and cell survival, but later on, it switches its function to induce a developmentally-regulated cell cycle arrest in the G1 phase and neuronal photoreceptor differentiation. To advance in the identification and characterization of regulators and targets of Dpp signaling required for retinal development, we carried out an in vivo eye-targeted double-RNAi screen to identify punt (Type II TGFβ receptor) interactors. Using a set of 251 genes associated with eye development, we identified CtBP, Dad, Ago and Brk as punt genetic interactors. Here, we show that downregulation of Ago, or conditions causing increased tissue growth including overexpression of Myc or CyclinD-Cdk4 are sufficient to partially rescue punt-dependent growth and photoreceptor differentiation. Interestingly, we show a novel role for the transcriptional co-repressor CtBP in inhibiting Dpp-dependent Mad activation by phosphorylation, downstream or in parallel to Dad, the inhibitory Smad. Furthermore, CtBP downregulation activates JNK signaling pathway, implying a complex regulation of signaling pathways by CtBP during eye development.
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10
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Xun Q, Bi C, Cui X, Wu H, Wang M, Liao Y, Wang R, Xie H, Shen Z, Fang M. MagT1 is essential for Drosophila development through the shaping of Wingless and Decapentaplegic signaling pathways. Biochem Biophys Res Commun 2018; 503:1148-1153. [PMID: 29959918 DOI: 10.1016/j.bbrc.2018.06.133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 06/23/2018] [Indexed: 12/01/2022]
Abstract
Magnesium transporter subtype 1 (MagT1) is a magnesium membrane transporter with channel like properties. We have previously identified MagT1 (CG7830) in Drosophila genome and characterized its protein product by electrophysiological means. Here, we report the generation of fly MagT1 mutants and show that MagT1 is essential for early embryonic development. In wings and primordial wings, by clonal analysis and RNAi knock down of MagT1, we have found that loss of MagT1 results in enhanced/ectopic Wingless (Wg, a fly Wnt) signaling and disrupted Decapentaplegic (Dpp) signaling, indicating the crucial role of MagT1 for fly development at later stages. Finally, we demonstrate directly that magnesium transportations are proportional with the MagT1 expressional levels in Drosophila S2 cells. Taken together, these findings may suggest that MagT1 is a major magnesium transporter/channel profoundly involved in fly development by affecting developmental signaling pathways, such as Wg and Dpp signaling.
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Affiliation(s)
- Qingying Xun
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China; Southeast University Medical School, Nanjing, 210009, China
| | - Caili Bi
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Xiaoying Cui
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Hongyan Wu
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Mingying Wang
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Yanlin Liao
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Rui Wang
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Hao Xie
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Zhijun Shen
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China
| | - Ming Fang
- Institute of Life Sciences, MOE Key Laboratory of Developmental Genes and Human Diseases, Southeast University, Nanjing, 210096, China.
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11
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Bellesis AG, Jecrois AM, Hayes JA, Schiffer CA, Royer WE. Assembly of human C-terminal binding protein (CtBP) into tetramers. J Biol Chem 2018; 293:9101-9112. [PMID: 29700119 DOI: 10.1074/jbc.ra118.002514] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 04/24/2018] [Indexed: 11/06/2022] Open
Abstract
C-terminal binding protein 1 (CtBP1) and CtBP2 are transcriptional coregulators that repress numerous cellular processes, such as apoptosis, by binding transcription factors and recruiting chromatin-remodeling enzymes to gene promoters. The NAD(H)-linked oligomerization of human CtBP is coupled to its co-transcriptional activity, which is implicated in cancer progression. However, the biologically relevant level of CtBP assembly has not been firmly established; nor has the stereochemical arrangement of the subunits above that of a dimer. Here, multi-angle light scattering (MALS) data established the NAD+- and NADH-dependent assembly of CtBP1 and CtBP2 into tetramers. An examination of subunit interactions within CtBP1 and CtBP2 crystal lattices revealed that both share a very similar tetrameric arrangement resulting from assembly of two dimeric pairs, with specific interactions probably being sensitive to NAD(H) binding. Creating a series of mutants of both CtBP1 and CtBP2, we tested the hypothesis that the crystallographically observed interdimer pairing stabilizes the solution tetramer. MALS data confirmed that these mutants disrupt both CtBP1 and CtBP2 tetramers, with the dimer generally remaining intact, providing the first stereochemical models for tetrameric assemblies of CtBP1 and CtBP2. The crystal structure of a subtle destabilizing mutant suggested that small structural perturbations of the hinge region linking the substrate- and NAD-binding domains are sufficient to weaken the CtBP1 tetramer. These results strongly suggest that the tetramer is important in CtBP function, and the series of CtBP mutants reported here can be used to investigate the physiological role of the tetramer.
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Affiliation(s)
- Andrew G Bellesis
- From the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and.,the Carlson School of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610
| | - Anne M Jecrois
- From the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and
| | - Janelle A Hayes
- From the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and
| | - Celia A Schiffer
- From the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and
| | - William E Royer
- From the Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and
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